COBALT-57

USES

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JPNM Physics Isotopes

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Co-57 is used as a radiolabel for Vit-B12 in Schilling's test. The determination of gastrointestinal absorption of Vit-B12 was among the initial tests offered by nuclear medicine laboratories, and continues to be a most useful procedure in the work-up and management of patients with megaloblastic anemia, suspected Vit-B12 deficiency and gastrointestinal malabsorption. More recently as a label for Bleomycin Co-57 has shown to be more sensitive than Ga-67 in the detection of certain tumors. Although the absorbed dose for patients with good renal function is low, the contamination hazards posed by the 270 days half-life radionuclide have prevented its widespread use. Unlike Ga-67, Co-57 Bleomycin is filtered by the kidneys with no localization in normal tissue.

Sisson and Beierwaltes first suggested Co-57 labeled Vit-B12 to identify the parathyroid gland by an unclear mechanism. Unfortunately, Vit-B12 Co-57 cannot be used for external detection of the abnormal parathyroid gland, since an excessive radiation is required to obtain sufficient radioistope concentration to identify the gland.

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Prepared by Luis E. Diaz, M.D.

References

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Douglas J. Wagenaar, Ph.D., wagenaar@nucmed.bih.harvard.edu